Systems based on the angular differentiation of pictures require the taking of a large number of pictures from different places and the projecting of the same number of pictures from different locations.
From the literature which deals with the taking of three-dimensional pictures, it is known that the maximum separation between the optical centres of the taking lenses for the reproduction to appear continuous is a function of the distance between the nearest object and the furthest object (depth of field) as well as of the distance between these objects with respect to the picture-taking device.
In order to apply these theoretical results in practice, in many cases of the prior art a separation is achieved between the optical centres of the taking lenses which is less than the breadth of the common, marketed or conventional cameras.
If the picture to be taken were to remain motionless, then it would be possible to do the taking with a conventional camera situated in a different place at each instant. However, if the picture were moving, this system would be inappropriate.
As far as the Applicant knows, there exist on the market very few cameras which can fulfill the conditions required for taking pictures. Those which are known have several lenses of small diameter and a likewise reduced negative format. These cameras are generally designed for their use in photography, and are used for reproducing still pictures in most cases as photographs on paper. A very small number of pictures, usually four, is used, which is entirely insufficient for systems based on the angular differentiation of pictures, and for this reason cannot be used in the present case.
Because of this lack of suitable cameras for taking three-dimensional pictures, it is necessary to take a large number of two-dimensional pictures, each one with a conventional camera; correspondingly, the same large number of projectors or projection lenses would be needed to reproduce the pictures taken three-dimensionally.
In the Ives U.S. Pat. No. 1,833,290, there are described three systems of reproduction by projection which are appropriate for still or moving pictures.
Of these three systems, that of back-projection is suitable only for systems based on the scalar differentiation of pictures, and therefore cannot be considered in the present case.
On the other hand, the other two systems, both of which are front-projection systems, can be employed for the angular differentiation of pictures.
In the first of these systems as many projectors and films are used as there are pictures.
The second system employs a single film in only one projector with as many lenses as pictures taken, the latter being mutually separated by the same distance as would occur if individual projectors were involved.
The disadvantage of both systems arises from the large volume occupied by the reproduction part of the system, as well as from the enormous length of the film and of the projector or projectors when the number of pictures is high.